Apparatuses and methods for providing a secondary reflector on a solar collector system

ABSTRACT

A solar collector system is provided that comprises an absorber tube, a primary reflector, and a secondary reflector. In certain embodiments, the primary and secondary reflectors are positioned on opposing sides of the absorber tube, such that their respective focal points converge upon a longitudinal axis of the absorber tube. The secondary reflector may be configured with a substantially transparent surface facing away from the absorber tube, so as to permit passage of light beams there-through. Opposing surfaces of the secondary and primary reflectors, namely those facing substantially toward the absorber tube contain a reflective coating thereon to facilitate redirection of light beams toward the absorber tube. The solar collector system includes in certain embodiments a frame assembly, whereby the primary reflector, the secondary reflector, and the absorber tube are all configured to unitarily rotate about a common pivot axis defined by at least a portion of the frame assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of both U.S.Provisional Application No. 61/548,536, entitled “Apparatuses andMethods for Providing a Secondary Reflector on a Solar Collector System”and filed Oct. 18, 2011, and U.S. Provisional Application No.61/560,590, entitled “Solar Thermal Energy Collector” and filed Nov. 16,2011, the contents of both of which are hereby incorporated herein intheir entirety.

BACKGROUND

1. Technical Field

Embodiments of the present invention relate generally to solarconcentrators and solar collector systems. More particularly, thevarious embodiments provide a solar concentrator that uses a secondaryparabolic reflector assembly in conjunction with an absorber tube and aprimary parabolic trough assembly to minimize the number of reflectedsolar rays that are never collected by the absorber tube.

2. Description of Related Art

Solar concentrators and solar collector systems work by collecting solarthermal energy (e.g., sunlight) from a large area and concentrating itinto a smaller area. Various types of solar concentrators and solarcollector systems exist and include at least parabolic solarconcentrators. Parabolic solar concentrators use mirrored surfacescurved in a parabolic shape to focus sunlight onto the mathematicalfocal point of their inherent parabola. When the parabolic solarconcentrator is dish shaped, the focal point is a discrete location;however, when the parabolic solar concentrator is trough shaped, thefocal point is a line (e.g., focal region). Trough-shaped parabolicsolar concentrators (e.g., parabolic troughs) typically include anelongated receiver tube, or heat collection element (HCE), which runsthe length of the trough. A longitudinal axis of the receiver tubegenerally corresponds to the focal region. In this manner, the parabolictrough focuses sunlight directly onto the receiver tube.

Parabolic trough solar concentrators are generally positioned in solarcollector system fields, often containing hundreds, if not thousands, ofadjacently positioned parabolic trough solar concentrators. Together,the multiple adjacently positioned parabolic trough solar concentratorsmay form a parabolic trough power plant. In such parabolic trough powerplants, a fluid, typically oil, runs through each of the receiver tubespositioned in the focal region of each of the parabolic troughs. Thefocused sunlight upon each of the elongated receiver tubes heats thefluid to high temperatures before the fluid passes through a heatexchanger, which generates steam. The steam may then be used to run aconventional power plant.

Most parabolic trough concentrators use a single axis parabolic mirrorthat must be accurately aligned with not only the sun, but also theelongated receiver tube so as to collect sunlight. Precision mirroralignment maximizes the reflected sunlight intercepting the elongatedreceiver tube, thereby improving overall collector efficiencies.However, focusing errors and thus geometrically dependent optical lossesoccur in parabolic trough collectors due to a variety of factors. Forexample, the mirror has a certain total shape tolerance, which mayinvolve some degree of waviness, both of which lead to focusing errors.Further, the positioning of the mirror during assembly is only possibleto within certain tolerances, likewise causing at least a portion of thereflected sunlight to miss (e.g., not intercept) the elongated receivertube. Self-deformation (e.g., warping), manufacturing, and assemblytolerances of the steel structure, on which the parabolic troughcollector is built, may also lead to inefficiencies. External factorssuch as the non-limiting examples of wind and dirt occurring in thevicinity of the parabolic trough and/or the elongated receiver tube mayalso cause deformations of portions of the structure sufficient toimpact sunlight collection efficiency.

Still further, as should be appreciated, the sun moves across the skyduring the day and is positioned at different locations in the skydepending upon the time of year thus presenting challenges in thecollection of solar light. Various parabolic trough concentrators andsolar collectors employ tracking device systems to facilitate pivotingthe primary reflectors some amount due to movement or positioning of thesun in order to collect solar light that would otherwise be lost. Areadjustment of the position of the concentrators and collectors may bemade, for example, every time the sun moves 3° across the sky. Althoughcapable of capturing some solar light, misalignment may occur since thetracking may not be completely accurate and small losses of solar lightfor each primary reflector add up to a large amount of loss for thesystem overall taking into account the large number of primaryreflectors that may be employed.

Although efforts have been made to minimize impacts of these variousfactors upon sunlight collection efficiency, not all factors may beentirely eliminated and/or avoided. As such, and because maximum energyefficiency remains desirable for at least cost and environmentalconcerns, a need exists for a parabolic trough collector that capturesand collects reflected at least an improved portion of sunlight thatwould otherwise be lost in various conventional systems. Such aparabolic trough collector having these and still other advantages isprovided by the various embodiments of the present invention.

SUMMARY OF THE INVENTION

The present invention generally relates to solar concentrators and solarcollector systems comprising secondary parabolic reflector assembliesfor use in conjunction with an absorber tube and a primary parabolictrough assembly so as to minimize the number of reflected solar raysthat are not initially collected by the absorber tube.

In accordance with various embodiments of the present invention asdescribed herein, a solar collector system is provided. The systemgenerally comprises: an absorber tube; a primary reflector having afirst side surface and an opposing second side surface, at least thefirst side surface being configured to substantially reflect one or morelight beams making contact therewith substantially toward the absorbertube; and a secondary reflector having a first side surface and anopposing second side surface, at least the first side surface beingconfigured to reflect the one or more light beams reflected from theprimary reflector further toward the absorber tube, wherein the absorbertube is positioned intermediate the primary reflector and the secondaryreflector, such that the absorber tube is configured to collect one ormore of the light beams reflected from the primary reflector and one ormore of the light beams reflected from the secondary reflector.

In accordance with various embodiments of the present invention asdescribed herein, an additional solar collector system is provided. Thesystem generally comprises: a frame assembly comprising a first supportmember, a second support member, and a third support member, the first,second, and third support members being operatively mounted relative toone another so as to define a unitary pivot axis; a primary reflector,the primary reflector being operatively attached to the first supportmember; a secondary reflector, the secondary reflector being operativelyattached to the second support member; and an absorber tube, theabsorber tube being operatively attached to the third support membersuch that the absorber tube is positioned intermediate the primaryreflector and the secondary reflector, wherein the primary reflector,the secondary reflector, and the absorber tube are each configured, viathe frame assembly, to rotate substantially about the unitary pivot axisalthough the primary reflector, the secondary reflector, and theabsorber tube each remain stationary relative to one another so as tominimize misalignment there-between.

In accordance with the various embodiments of the present invention asdescribed herein, a method of using a solar collector system to maximizecollection of light beams directed thereon by an external light sourceis also provided. The method comprises the steps of: (A) providing asystem comprising: (1) a frame assembly comprising a first supportmember, a second support member, and a third support member, the first,second, and third support members being operatively mounted relative toone another so as to define a unitary pivot axis; (2) a primaryreflector, the primary reflector being operatively attached to the firstsupport member; (3) a secondary reflector, the secondary reflector beingoperatively attached to the second support member; and (4) an absorbertube, the absorber tube being operatively attached to the third supportmember such that the absorber tube is positioned intermediate theprimary reflector and the secondary reflector; (B) positioning saidsolar collector system in a first orientation, said first orientationcorresponding to a position at which, during a first period of time, avolume of light beams directed onto said primary reflector is maximized;and (C) rotating said solar collector system to a second orientation,said second orientation corresponding to a position at which, during asecond period of time different from said first period of time, saidvolume of light beams directed onto said primary reflector is maximized,wherein said rotating occurs about said unitary pivot point such thatthe primary reflector, the secondary reflector, and the absorber tubeeach remain stationary relative to one another so as to minimizemisalignment there-between.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The accompanying drawings incorporated herein and forming a part of thedisclosure illustrate several aspects of the present invention andtogether with the detailed description serve to explain certainprinciples of the present invention. In the drawings, which are notnecessarily drawn to scale:

FIG. 1 illustrates a generic parabola and its focus;

FIG. 2 illustrates incident light reflecting on the generic parabola ofFIG. 1;

FIG. 3 is a front perspective view of a parabolic solar collectoraccording to various embodiments;

FIG. 4 is a rear perspective view of the parabolic solar collector ofFIG. 3, positioned in a first orientation according to variousembodiments;

FIG. 4A is a front perspective view of the absorber tube assembly 140and its associated elements of the mounting assembly 180 according tovarious embodiments;

FIG. 5 is another rear perspective view of the parabolic solar collectorof FIG. 3, positioned in a second orientation according to variousembodiments;

FIG. 5A is a front perspective view of the secondary reflector assembly160 and its associated elements of the mounting assembly 180 accordingto various embodiments;

FIG. 6 is a top perspective view of the parabolic solar collector ofFIG. 3, positioned in a third orientation according to variousembodiments;

FIG. 7 is a side view of the parabolic solar collector of FIG. 3;

FIG. 8 is a front perspective view of a group of the parabolic solarcollectors of FIG. 3 according to various embodiments;

FIG. 9 is a rear perspective view of the group of parabolic solarcollectors of FIG. 8 according to various embodiments;

FIG. 10 is a front perspective view of a plurality of the parabolicsolar collectors of FIG. 3 according to various embodiments;

FIG. 11 is a top perspective view of the plurality of parabolic solarcollectors of FIG. 10 according to various embodiments;

FIG. 12 is a rear perspective view of the plurality of parabolic solarcollectors of FIG. 10 according to various embodiments;

FIG. 13 is a side view of a parabolic solar collector according to oneexemplary embodiment;

FIG. 14 is a side view of a parabolic solar collector according toanother exemplary embodiment;

FIG. 15 is a side view of a parabolic solar collector according to yetanother exemplary embodiment; and

FIG. 16 is a perspective view of an alternative base assembly 110according to various embodiments.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

Various embodiments of the present invention will now be described morefully hereinafter with reference to the accompanying drawings, in whichsome, but not all embodiments of the invention are shown. Indeed,embodiments of the invention may be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Unless otherwise defined, alltechnical and scientific terms used herein have the same meaning ascommonly known and understood by one of ordinary skill in the art towhich the invention relates. The term “or” is used herein in both thealternative and conjunctive sense, unless otherwise indicated. Likenumbers refer to like elements throughout.

Overview

As commonly known and understood in the art, parabolic solarconcentrators use mirrored surfaces curved in a parabolic shape to focussunlight onto the mathematical focal point of their inherent parabola.FIG. 1 depicts a traditional generic parabolic shape 10 that isgenerally used to form such mirrored surfaces. Mathematically speaking,a parabola is the set of points in a plane that are equidistant from afocal point 12 and a line 13 in the plane, typically referred to as adirectrix. The various embodiments of the present invention, like othercommonly known parabolic solar concentrators utilize mirrored surfacesformed in the generic parabolic shape 10. It is understood thatvirtually any parabolic arc (e.g., mathematical equation) may beutilized according to various embodiments, as the alignment of variousstructural elements along the parabolic shape 10 and its focal point 12is determinative.

FIG. 2 depicts at least a portion of the traditional generic parabolicshape 10 also illustrated in FIG. 1, but further depicting a pluralityof incident light rays 14 impacting a surface of the parabolic shape 10.A plurality of reflected light rays 15 are also illustrated, extendingfrom the point of impact between the incident light rays 14 and theparabolic shape 10 to the focal point 12. Due to the mathematicalequations governing parabolic shapes such as that shown in thesefigures, such incident light rays 14, once reflected from a reflectingsurface of the parabolic shape 10 will always converge upon the focalpoint 12.

Element List

-   -   100 solar concentrator        -   110 base assembly            -   112 foundation member            -   114 upright support member            -   115 cross member    -   120 parabolic trough assembly        -   122 mirror            -   123 first reflective surface            -   124 second surface            -   125 first edge            -   126 second edge            -   127 first side            -   128 second side        -   129 elongate structural frame member            -   130 first end            -   131 second end        -   132 structural support members            -   133 first end            -   134 second end    -   140 absorber tube        -   142 first end        -   143 second end        -   146 medial portion    -   140A alternative absorber tube #1    -   140B alternative absorber tube #2    -   160 secondary reflector assembly        -   162 mirror            -   163 first reflective surface            -   164 second surface            -   165 first edge            -   166 second edge            -   167 first side            -   168 second side        -   169 elongate structural frame member            -   170 first end            -   171 second end        -   172 structural support members    -   160A alternative secondary reflector assembly #1    -   160B alternative secondary reflector assembly #2    -   180 mounting assembly        -   181 drive bracket        -   183 exemplary drive mechanism        -   184 central bracket        -   186 trough support bracket        -   188 absorber tube support bracket            -   189 elongate tube support members        -   190 secondary reflector support bracket            -   192 elongate reflector support members

Structure of Various Embodiments

Various embodiments utilize the traditional generic parabolic shape 10,as previously described with reference to FIGS. 1 and 2 to provide asolar concentrator 101 that comprises at least a base assembly 110, aparabolic trough assembly 120, an absorber tube 140, a secondaryreflector assembly 160, and a mounting assembly 180.

Base Frame Assembly 110

Turning now to FIG. 3, the solar concentrator 101 according to variousembodiments is illustrated, comprising at least a base frame assembly110. As may be seen from this figure, in conjunction with FIG. 4, thebase frame assembly 110 may, in various embodiments include a basemember 112, an elongate upright support member 114, and a plurality ofcross support members 115. In certain, and at least the illustratedembodiment, the base frame assembly 110 may incorporate two base members112 and two support members 114, each respectively positioned onsubstantially opposing sides of the parabolic trough assembly 120, whichthey support, as described in further detail below. Of course, it shouldbe understood that in other embodiments, a singular base member 112 anda singular support member 114 may be instead used.

The base member 112 may in certain embodiments be constructed from asteel material, although any of a variety of materials may be used,provided such materials exhibit properties sufficient to support theremaining assemblies, as will be described in further detail below. Thebase member 112 may also, in certain embodiments, be further positionedatop a concrete foundation (see, for example, FIG. 16), or the like, ascommonly known and understood in the art to rigidly and securely retainstructural assemblies analogous to the assembly 110.

The elongate upright support members 114 may, according to variousembodiments, be operatively attached at one end to a surface of the basemember 112, generally positioning the two relative to one another, asshown in at least FIGS. 3 and 4. The elongate support member 114 may beformed from any of a variety of structural materials, although suchshould likewise exhibit material properties sufficient to support theremaining assemblies, as will be described in further detail below. Incertain embodiments, the elongate upright support member 114 may includea plurality of cross support members 115, configured to provideadditional structural support and/or strength, as may be necessary for aparticular environment.

With continued reference to FIGS. 3 and 4, the base member 112 may beconfigured according to various embodiments for bolting to a concretepad (not shown), whether under or immediately atop the ground surface(shown, but not numbered). In other embodiments, however, the basemember 112 may simply rest directly on the ground surface, provided suchis sufficiently level and stable for a desired purpose. Each of theupright support members 114 are further located on opposite ends of thesolar concentrator 100 in a longitudinal direction 70 of the solarconcentrator 100, as will be described in further detail below withreference to a sole pivot axis 180A of the solar concentrator.

In any of these and still other embodiments, it should be understoodthat although the base frame assembly 110 has been described as above,according to exemplary embodiments illustrated in at least FIGS. 3 and4, the assembly 110 may, in other embodiments be configured andconstructed in any of a variety of shapes or sizes, as are commonlyknown and used in the art for supporting solar collectors such as theconcentrator 101. Consider, for example, that in certain embodiments,the assembly 110 may include a unitary support member, without the needfor separate base and upright members 112, 114, as previously describedherein. Consider further that in any of those or even other embodimentshaving a unitary support member so configured, the member may further,as a single piece, support both sides of the parabolic trough assembly120, as will be described in further detail below. At least onenon-limiting exemplary alternative base assembly 110A is illustrated inat least FIG. 16.

Parabolic Trough Assembly 120

As with the base frame assembly 110, as previously described herein,various configurations of parabolic trough assemblies are commonly knownand used in the art in conjunction with solar concentrators and/or solarcollector systems. Generally speaking, as may be understood from FIGS. 5and 6, which illustrate an exemplary parabolic trough assembly 120, suchassemblies include at least a mirror 122 and one or more structuralmembers (e.g., 129, 132). The mirror 122 according to variousembodiments typically includes a multi-layer first concave surface 123that comprises a reflective layer, and a second convex back surface 124to which the structural members 129, 132 are mounted. The mirror 122according to various embodiments is defined further by a first angularedge 125, a second angular edge 126, a first side 127, and a second side128, each of which will be described in further detail below.

The mirror 122 of the parabolic trough assembly 120 according to variousembodiments is parabolic shaped (as has been described previously hereinwith regard to at least FIGS. 1 and 2) and may be formed from asubstrate having a reflective layer. The substrate may be glass or metalbased, as is commonly known and understood in the art. Glass is oftenchosen as at least an exterior substrate layer of the first surface 123of the mirror 122 because it prevents abrasion and/or corrosion ofinterior substrate layers, such as, for example, the reflective layer.Although glass is brittle, it is a good material for such purposes, asit is highly transparent (e.g., causing minimal optical losses),resistant to ultraviolet radiation (e.g., having a long life cycle),chemically inert, and fairly easy to clean. Metal substrates, as may beemployed in certain embodiments, are lighter and stronger than glass,while also being relative inexpensive.

As mentioned, the glass substrate layer may generally comprise areflective layer, typically formed from a thin metal film, as iscommonly known in the art. In at least certain embodiments, the metalfilm (not shown) may be constructed from a polished silver material,while in other embodiments the film may be constructed from a polishedaluminum material or may be deposited onto a substrate by any of avariety of well-known vapor deposition processes. In still otherembodiments, the thin metal film may be constructed from any of avariety of materials, as may be desirable for a particular application.However, it should be understood that in any of these and otherenvisioned embodiments, the reflective layer and/or metal film isshielded by the exterior glass substrate layer from abrasion andcorrosion.

Turning in particular now to FIG. 5, the back surface 124 of the mirror122 of the parabolic trough assembly 120 is illustrated, as attached tothe structural members 129, 132, each of which will now be described infurther detail. The elongate structural frame member 129 according tovarious embodiments includes a first end 130 and a second end 131, whichare generally positioned adjacent the corresponding first side 127 andsecond side 128 of the mirror 122. In certain embodiments, the elongatestructural frame member 129 may be operatively connected to the firstside 127 and/or the second side 128 of the mirror; however, in otherembodiments, as illustrated in FIG. 5, the frame member 129 may be atleast partially spaced relative to the mirror 122 by a plurality ofstructural support members 132, as will be described below.

The plurality of structural support members 132, as may be seen in atleast FIGS. 4 and 5, are according to various embodiments generallyelongate and have a first end 133 and a second end 134. The first end133 of each of the members 132 may, in certain embodiments, beoperatively connected to the mirror 122 substantially adjacent a firstor a second angular edge 125, 126 of the mirror, as previously describedherein. In other embodiments, however, the first end 133 may beotherwise attached, via a variety of mechanisms and at a variety oflocations, as may be suitable for a particular application. The secondend 134 of each of the members 132 may, in certain embodiments, beoperatively connected to the mirror 122 and/or just the frame member 129adjacent a substantially center portion (shown, but not numbered in FIG.5) of the mirror. It should be understood that in at least thoseembodiments in which the mirror 122 is substantially parabolic in shape,the members 132 are correspondingly formed into a parabolic shape alongat least a portion of their length. In this manner, each of theplurality of structural support members 132, when present in conjunctionwith the elongate frame member 129, form a structural web of sufficientstrength to support, from behind (or below), the parabolic troughassembly 120. In any of these and still other embodiments, it should beunderstood that the elongate length of the members 132 may roughlycorrespond to the length of the arc formed by the mirror 122, althoughthe two may vary, as may be desirable for a particular application.

In various embodiments, the mirror 122 defines a parabolic arc having adiameter of approximately fix (5) meters. Of course, in certainembodiments, the diameter of the mirror 122 may be less than or greaterthan five meters, as may be desirable for a particular application. Incertain embodiments, the diameter may range from three to seven meters.In other embodiments, the diameter may even be less than three or morethan seven meters, as may be suitable for a particular application. Instill other embodiments, the mirror 122 may define a shape other than aparabolic arc, but with any of the above-described comparable diameters,or even further alternative diameters, also as may be desirable for aparticular application. It should be understood that in any of thesevarious embodiments, relative size characteristics of the mirror 122 aretypically limited at least in part by the structural strengthcharacteristics of the base assembly 110, as previously described.

In various embodiments in which the mirror 122 defines a parabolic arc,it should be understood that the mirror 122 further defines a focalpoint, at which at least the absorber tube 140, as will be described infurther detail below, should be positioned. Such is at least in part dueto the focal point's mathematical definition as the point at which lightrays reflected from parabolic arcs converge. In certain embodiments, thefocal point (see, e.g., FIGS. 1 and 2) may be located approximately 2.0to 2.5 meters from the mirror 122. In other embodiments, the focal pointmay be located anywhere from 1.5 to 4.5 meters from the mirror 122. Instill other embodiments, the focal point may be located any of a varietyof distances from the mirror, as may be mathematically determined fromthe relative diameter (D) and depth (d) of the parabolic arc defined bythe mirror 122. The focal point may calculated, for example, by dividingthe square of the diameter by the result of multiplying the depth by 16,mathematically represented at focal point (F)=D²/(16d). Still further,it should be understood that relative size characteristics of the mirror122 directly influence relative size characteristics and relativepositioning considerations of the absorber tube 140, as the latter,regardless of relative size, must be positioned at the focal point (see,e.g., point 12 of FIG. 1) of the mirror 122, all of which will bedescribed in further detail below.

With particular reference to FIG. 6, according to various embodiments,the mirror 122 may be formed from two adjacently positioned mirrorpanels, each having length dimensions as previously described herein. Inthese and other embodiments, it should be understood that the parabolicarc length of each of the two adjacently positioned mirror panels may beapproximately half that of the entire mirror 122. In still otherembodiments, the mirror 122 may be formed from a single unitary mirrorpanel, having both length and parabolic arc dimensions as previouslydescribed herein. In certain embodiments, however, as may be suitablefor a particular application, the mirror 122 may be still further formedfrom a plurality of mirror panels, each aligned adjacently relative toone another, as may be seen in at least FIG. 3. In at least theillustrated embodiment, the mirror panels may be sized and shaped suchthat, when combined, the arc length of the mirror 122 is approximatelysix (6) meters (or otherwise dimensioned), meaning at least a portion ofits circumference may be truncated, as previously described herein. Inthose embodiments having two adjacently positioned mirror panels, eachof the respective panels may have a parabolic arc length ofapproximately half that of the entire mirror 122, while in alternativeembodiments having a single unitary mirror 122, the parabolic arc lengthof such panels would correspond to that of the mirror. Of course, stillother mirror panel or parabolic reflector configurations may besubstituted as suitable for a particular application, as many of avariety of such configurations are known and used in the art.

The various structural members 129, 132 may be formed from any of avariety of structural materials as commonly known and used in the artfor such applications, provided such materials exhibit propertiessufficient to support at least the mirror 122 and the remainingassemblies, each as will be described in further detail below. It shouldbe understood, again, that although the parabolic trough assembly 120has been described above as including a mirror 122 and one or more ofsuch structural members 129, 132, various alternatively configuredparabolic trough assemblies are commonly known and used in the art inconjunction with solar concentrators and/or solar collector systems. Assuch, any of these, or still other envisioned parabolic troughassemblies may, in still other embodiments, be substituted for theassembly 120 described herein, as may be desirable for a particularapplication.

Absorber Tube 140

As with the base frame assembly 110 and the parabolic trough assembly120, each as previously described herein, various configurations ofabsorber tubes are commonly known and used in the art in conjunctionwith solar concentrators and/or solar collector systems. Generallyspeaking, as may be understood from FIGS. 4 and 5, in which an exemplaryabsorber tube 140 may be seen, such tubes typically include at least afirst end 142, a second end 144, and a medial portion 146. The first andsecond, typically opposing ends 142, 144 may, according to variousembodiments, be positioned such that they're aligned relative to thefirst and second sides 127, 128 of the mirror 122 of the parabolictrough assembly 120. Such facilitates their relative positioning via themounting assembly 180, as will be described in further detail below.

The medial portion 146 of the absorber tube 140, as is commonly knownand understood in the art, is configured to absorb the reflectedsunlight 14 (see, e.g., FIG. 2) that converges upon the parabolic focalpoint 12 (e.g., where the absorber tube is itself positioned). As hasbeen described previously herein, and also commonly known and understoodin the art, a fluid, such as oil or water, typically flows through theabsorber tube 140 and is heated by the reflected sunlight 14 thatreaches the tube from the parabolic mirror 122. The fluid may, accordingto certain embodiments, be located and transported within an inner tube(see, for examples, FIGS. 13-15) of the absorber tube that is surroundeditself by a concentric outer tube (see, for examples, FIGS. 13-15).Typical outer tubes are made of glass, so that solar thermal energy(e.g., reflected sunlight 14) directed thereto by the mirror 122 is notunduly impeded from reaching the inner tube and thus the fluid containedtherein. The space between the inner tube and the outer tube may, incertain embodiments be evacuated such that a vacuum is formed, as iscommonly known and understood in the art. This vacuum functions toreduce heat transfer from the heated fluid and the inner tube backthrough and to the outer tube. Preventing temperature increases in theouter tube, amongst other things, increases the efficiency of theparabolic trough assembly 120 and enhances safety by minimizing risk ofthe outer tube becoming too hot to touch.

As has been previously described herein, the absorber tube 140 shouldgenerally be configured with respect to at least the parabolic troughassembly 120, such that a central longitudinal axis of the tube 140corresponds to an axis passing through the focal point (e.g., seeFIG. 1) of the mirror 122 of the assembly 120. In certain embodiments,the tube 140 may be located approximately 2.0 to 2.5 meters from themirror 122. In other embodiments, the tube 140 may be located anywherefrom 1.5 to 4.5 meters from the mirror 122. In still other embodiments,the tube 140 may be located any of a variety of distances from themirror, provided the tube corresponds to the focal point, which may becalculated, as previously described from the diameter (D) and the depth(d) of the mirror 122, expressed as the focal point (F)=D²/(16d).

In various embodiments, the absorber tube 140 has a length ofapproximately six (6) meters. Of course, in certain embodiments, thelength may be less than or greater than six meters, as may be desirablefor a particular application. Further, in various embodiments, the innertube of the absorber tube 140 has a diameter of approximately 70millimeters while the outer tube has a diameter of approximately 115millimeters. In certain embodiments, the inner and outer tube diametersmay be less than or greater than 70 and 115 millimeters, respectively,as may be desirable for a particular application. However, suchdiameters should be considered exemplary and further, generallyrepresentative of diameters of conventional absorber tubes, as commonlyknown and used in the art.

In various embodiments, the diameter of the inner tube of the absorbertube 140 is related to the diameter of the mirror 122 of the parabolictrough assembly 120 by a ratio of approximately 1 to 100. For example,in those embodiments in which the mirror 122 has a diameter of seven (7)meters, the inner tube has a diameter of approximately 70 millimeters.In other embodiments, in which the mirror 122 has a diameter of five orthree meters, the inner tube may have a diameter of approximately 50 or30 millimeters, respectively. Of course, it should be understood thatany of a variety of relative ratios between the diameter of the absorbertube 140 and that of the mirror 122 may be selected, as may be desirablefor a particular application, in which case the examples provided hereinshould be considered non-limiting.

With reference to at least FIGS. 13-15, it should be understood that theabsorber tube 140 may be alternatively configured, wherein asnon-limiting examples an absorber tube 140A may be formed withsubstantially square-shaped cross-sections, as compared to thesubstantially circular cross-sections found in absorber tube 140. Stillfurther alternatives are illustrated via absorber tube 140B (see FIG. 15specifically), wherein the inner tube may have a cross-section differingfrom that of the outer tube, such that at least one may be substantiallysquare-shaped while the other is substantially circular-shaped. Ofcourse, still other possibilities exist, wherein the cross-sections ofone or more of the inner/outer tubes of an absorber tube 140 may betriangular-shaped, irregularly shaped, or otherwise configured, as maybe desirable for particular applications. In certain embodiments, theinner/outer tubes may also be concentric relative to one another,generally as illustrated in FIGS. 13-15; however, in still otherembodiments (not shown), the two need not necessarily be concentricallyconfigured.

Still further, it should be understood that any of a variety ofconfigured absorber tubes, as commonly known and used in the art inconjunction with parabolic and other configured solar collector systems,may be used in certain embodiments of the present invention, in place ofthe exemplary absorber tube 140, as has been described herein. Indeed,consider, for example, the absorber tube of U.S. Patent ApplicationPublication No. 2010/0126499 to Wei David Lu, which describes aparticular absorber tube that further includes an expansion elementconfigured to expand or contract in response to differences in thermaltemperatures between the inner tube and outer tube. This application,amongst other things, further describes a variety of getters, locatedradially between the inner and outer tube, so as to capture excesshydrogen that leaks from the heated inner tube into the vacuum sealedouter tube. Any variety of such absorber tubes, amongst others furtherknown and used in the art may be incorporated into the present solarconcentrator 101, as may be desirable for a particular application.

Secondary Reflector Assembly 160

As may be understood from FIGS. 4-6, a secondary reflector assembly 160(see FIG. 4) according to various embodiments may include at least amirror 162 (see FIG. 5) and one or more structural members 169, 172 (seeFIG. 6). With particular reference to FIG. 5, it may be seen that themirror 162 according to certain embodiments includes a first surface 163that comprises a reflective layer, and a second surface 164 to which thestructural members 169, 172 are mounted. Still further, the mirror 162according to various embodiments is defined by a first angular edge 165,a second angular edge 166, a first side 167, and a second side 168, eachof which will be described in further detail below. The mirror 162 mayalso, in certain embodiments, be parabolic in shape, just as the mirror122, although in other embodiments, various alternative shapes of themirror 162 may be envisioned, depending on a particular application. Itshould be understood for at least those embodiments having aparabolic-shaped mirror 162, the mathematical characteristics of suchmirror will generally be substantially different than that of the mirror122, as previously described herein, at least in part to obtain a muchshorter focal length of mirror 162, as compared to that of mirror 122.

Turning now to FIG. 6, an exemplary parabolic mirror 162 of thesecondary reflector assembly 160 according to various embodiments isillustrated, as formed from a substrate having a reflective layer. Incertain embodiments, the parabolic mirror 162, and in particular itssubstrate having a reflective layer may be sized, shaped, and configuredsubstantially the same as the analogous features of mirror 122, aspreviously described herein. Of course, in still other embodiments, itshould be understood that any combination of the features of mirror 162may be substantially different from those corresponding features ofmirror 122, as may be desirable for a particular application.

Turning in particular now to FIG. 5, the mirror 162 of the secondaryreflector assembly 160 is illustrated, as attached to the structuralmembers 169, 172, each of which will now be described in further detail.The elongate structural frame member 169 according to variousembodiments includes a first end 170 and a second end 171, which aregenerally positioned adjacent the corresponding first side 167 andsecond side 168 (see FIG. 4) of the mirror 162. In certain embodiments,the elongate structural frame member 169 may be operatively connected tothe first side 167 and/or the second side 168 of the mirror; however, inother embodiments, as illustrated in FIG. 5, the frame member 169 may beat least partially spaced relative to the mirror 162 by a plurality ofstructural support members 172, as will be described below. Stillfurther, a plurality of cross-support members 175 may be incorporatedwithin the structural member 169, as may be suitable for a particularapplication, wherein additional strength of the member may be necessaryor desirable.

The plurality of structural support members 172, as may be seen in atleast FIG. 6, are according to various embodiments generally elongateand curved in a fashion corresponding substantially to the shape of themirror 162. As a non-limiting example, for those embodiments in whichthe mirror 162 is substantially parabolic in shape, the members 172 arecorresponding formed into a parabolic shape along their length. Incertain embodiments, the members 172, when so formed, may be operativelyfastened to at least a portion of the mirror 162 substantially adjacenta first or a second angular edge 165, 166 of the mirror, as previouslydescribed herein. In other embodiments, however, the members 172 may beotherwise attached, via a variety of mechanisms and at any of a varietyof locations, as may be suitable for a particular application. However,regardless of how precisely attached to the mirror 162, it is in thismanner that each of the plurality of structural support members 172,when present in conjunction with the elongate frame member 169, form astructural web of sufficient strength to support, from behind (or above,as may the case be), at least the mirror 162 of the second reflectorassembly 160. In any of these and still other embodiments, it should beunderstood that the elongate length of the members 172 may roughlycorrespond to the length of the arc formed by the mirror 162.

In various embodiments, the mirror 162 defines a parabolic arc having adiameter of approximately two (2) meters. Of course, in certainembodiments, the diameter of the mirror 162 may be less than or greaterthan two meters, as may be desirable for a particular application. Incertain embodiments, the diameter may range from one to three meters. Inother embodiments, the diameter may even be less than one or more thanthree meters, as may be suitable for a particular application. In stillother embodiments, the mirror 162 may define a shape other than aparabolic arc, but with any of the above-described comparable diameters,or even further alternative diameters, also as may be desirable for aparticular application. It should be understood that in any of thesevarious embodiments, relative size characteristics of the mirror 162 aretypically limited at least in part not only by the structural strengthcharacteristics of the base assembly 110, but also by a desire tominimize the obstruction of any sunlight rays from reaching the mirror122 of the parabolic trough assembly 120.

In various embodiments in which the mirror 162 defines a parabolic arc,it should be understood that the mirror 162 further defines a focalpoint, at which at least the absorber tube 140, as will be described infurther detail below, should be positioned. Such is at least in part dueto the focal point's mathematical definition as the point at which lightrays reflected from parabolic arcs converge. In certain embodiments, thefocal point (see, e.g., FIGS. 1 and 2) may be located approximately 0.5to 1.5 meters from the mirror 162. In other embodiments, the focal pointmay be located anywhere from 0.25 to 2.5 meters from the mirror 162. Instill other embodiments, the focal point may be located any of a varietyof distances from the mirror, as may be mathematically determined fromthe relative diameter (D) and depth (d) of the parabolic arc defined bythe mirror 162. The focal point may calculated, for example, by dividingthe square of the diameter by the result of multiplying the depth by 16,mathematically represented at focal point (F)=D²/(16d). Still further,it should be understood that relative size characteristics of the mirror162 directly influence relative size characteristics and relativepositioning considerations of the absorber tube 140, as the latter,regardless of relative size, must be positioned at the focal point (see,e.g., point 12 of FIG. 1) of the mirror 162, all of which will bedescribed in further detail below.

In various embodiments, the mirror 162 has an arc length ofapproximately three (3) meters. Of course, in certain embodiments, thelength of the mirror 162 may be less than or greater than three meters,as may be desirable for a particular application. However, it should beunderstood that the length of the mirror 162 in any of these and stillother embodiments should be substantially less than to the arc length ofthe mirror 122, so as to minimize the risk of the mirror 162 in blockinga significant degree of incident light rays from reaching the mirror 122of the parabolic trough assembly 120. Of course, a competingconsideration according to various embodiments is that the greater thearc length of the mirror 162, the more efficient the system, as a wholemay be, as the larger sized mirror 162 will more effectively capture abroader scope of re-reflected light rays, that for whatever reason, donot converge upon the absorber tube 140.

In certain embodiments, wherein a maximal size of mirror 162 isdesirable with minimal blockage of incident sunlight rays, the mirror162 may be constructed from a glass substrate having a very thin andsparsely applied reflective layer, such that a desired portion of theincident light rays may pass unimpeded through the mirror 162 from atop(e.g., the side facing the sun), but the same light rays, once reflectedfrom the mirror 122 and having missed the absorber tube 140, are notpermitted to pass back through unimpeded, instead being re-reflectedtoward the absorber tube. Such mirrors, commonly referred to as “one-waymirrors” are commonly known and used in the art, and still further inother applications, such as the one-way mirrors employed by policeofficers when interrogating suspects.

As with mirror 122 (previously described herein), the mirror 162according to various embodiments may be formed from two adjacentlypositioned mirror panels (best illustrated in FIG. 5), each havinglength dimensions as previously described herein. In these and otherembodiments, it should be understood that the parabolic arc length ofeach of the two adjacently positioned mirror panels may be approximatelyhalf that of the entire mirror 162. In still other embodiments, themirror 162 may be formed from a single unitary mirror panel, having bothlength and parabolic arc dimensions as previously described herein. Incertain embodiments, however, as may be suitable for a particularapplication, the mirror 162 or parabolic reflector may still further, oralternatively, be formed from a plurality of individual mirror panels,each aligned adjacently relative to one another, as may be bestunderstood again from FIG. 5. In at least the illustrated embodiment,the mirror panels may be sized and shaped such that, when combined, themirror 162 length is approximately six (6) meters (or otherwisedimensioned), as previously described herein. Of course, still othermirror panel and parabolic reflector configurations may be substituted,as may be suitable for a particular application.

The various structural members 169, 172 may be formed from any of avariety of structural materials as commonly known and used in the artfor such applications, provided such materials exhibit propertiessufficient to support at least the mirror 162. As a non-limitingexample, in certain embodiments, the structural members 169, 172 may beformed from substantially the same materials as analogous members 129,132, as previously described herein. In other embodiments, the materialstrength requirements for the structural members 169, 172 may be lesserthan that for members 129, 132, in which case alternatively configuredmaterials may be substituted, as may be suitable for particularapplications. Still further, although the structural members 129, 132,169, and 172 have been described herein as substantially the same inshape and size configuration, certain embodiments may contain variouscombinations of configurations, provided the length of each of thestructural members remains substantially equivalent to that of theothers, as will be described in further detail below with regard to themounting assembly 180.

As described previously with regard to FIG. 2, incident light rays 14,once reflected from a reflecting surface of a parabolic shape 10 willalways converge upon a focal point 12 of the parabolic shape. As such,because the absorber tube 140 is positioned at the focal point 12 of theparabolic trough, most (if not, in some instances all) of the incidentlight rays 14, once reflected as rays 15, will converge upon theabsorber tube. However, due to various factors, as have been describedpreviously herein, inefficiencies may arise over time, causing at leasta portion of the reflected rays 15 to miss the absorber tube 140. Forthe secondary reflector assembly 160 to address this concern, which isat least one intended advantage thereof, the mirror 162 of the assemblymust likewise be positioned relative to the absorber tube 140 such thatthe reflected rays 15, once further reflected off the mirror 162,converge again upon the absorber tube. In other words, the absorber tube140 according to various embodiments, should generally not only bepositioned substantially at the focal point of the mirror 122 of theparabolic trough assembly 120, but also at the focal point of the mirror162 of the secondary reflector assembly 160, as may be understood fromat least FIG. 5.

With reference now to FIGS. 13-15, various non-limiting and exemplaryembodiments of secondary reflector assemblies are illustrated. Withparticular reference to FIG. 13, a secondary reflector assembly 160 isillustrated, as has been primarily described previously herein, whereinthe assembly is substantially parabolic in shape, as is the parabolictrough assembly 120 (also sometimes referred to as the primary reflectorassembly). As may be seen a light beam A of solar light may contact theparabolic trough assembly 120 but then subsequently miss the absorbertube 140. When such occurs, energy contained in the light beam A is lostand not captured by the solar concentrator 100, thereby creatingunintended inefficiencies, as previously described herein. However, dueto the configuration of the secondary reflector assembly 160 the missedlight beam A is redirected onto the absorber tube 140. In certainembodiments, the secondary reflector assembly 160 may be configured witha single focal point, although in other embodiments, the reflectorassembly may have multiple focal points, as will be described laterherein.

With continued reference to FIG. 13, additional light beams B and C arealso illustrated, that might likewise otherwise miss the absorber tube140 but for the presence of the secondary reflector assembly 160. Incertain embodiments, the secondary reflector assembly 160 may beconfigured such that different light beams B and C (including thoseother than shown) may hit the parabolic trough assembly 120 at differentlocations and angles of incidence are all, in fact, redirectedsufficiently toward the secondary reflector assembly 160 so as for themto ultimately contact the absorber tube 140. It should be furtherunderstood that, as has been previously described herein, the “one-way”mirror construction of at least the secondary reflector assembly 160facilitates passage of light beams such as beam C to pass through thesecondary reflector assembly, as illustrated in FIG. 13, substantiallyunimpeded.

Turning now to FIGS. 14 and 15, it should be understood that, as withthe absorber tube 140, there may likewise be various alternativeembodiments of the secondary reflector assembly 160. As a non-limitingexample, as opposed to the parabolic shape illustrated in FIG. 13, anexemplary secondary reflector assembly 160A may be configured as asubstantially planar surface. FIG. 15 illustrates yet anothernon-limiting example, in which an additional exemplary secondaryreflector assembly 160B may be constructed with a dual-parabolic shape.In other words, certain embodiments of at least secondary reflectorassembly 160B may have at least two parabolic shaped sections that arelocated substantially adjacent one another. In at least one embodiment,the two may not necessarily touch or engage one another, as may bedesirable for particular applications. Of course, still furtherembodiments may have secondary reflector assemblies configured in any ofa variety of constructions, as may be desirable, provided suchnevertheless operate to substantially redirect otherwise lost incidentbeams A, as illustrated in FIGS. 13-15.

Mounting Assembly 180

As may be understood from FIGS. 4, 5 and 7, the solar concentrator 101may include one or more mounting assemblies 180 (see FIG. 4), whichaccording to various embodiments may be configured to provide aninterface between the parabolic trough assembly 120 and the baseassembly 110. In certain embodiments, the mounting assemblies 180 mayinclude at least a drive bracket 181 (see FIG. 7), a central bracket 184(see FIG. 4), an absorber tube bracket 186 (see FIG. 4), and a secondaryreflector bracket 190 (see FIG. 5). It should be understood from atleast FIG. 7 that the solar concentrator 101 may according to variousembodiments generally include at least two mounting assemblies 180, eachpositioned on a substantially opposing side of the remaining assemblies(e.g., 120, 140, 160) so as to jointly support at least those assembliesthere-between. In other embodiments, of course, it should be understoodthat alternatively configured mounting assemblies may be envisioned,provided such do not unduly impact the degree of incident sunlight thatreaches the mirror 122 of the parabolic trough assembly 120 from the sunor other source.

With particular reference to FIG. 7, it may be seen that the drivebracket 181 of the mounting assembly 180 provides the sole pivotingconnection point between the base assembly 110 of the solar concentrator101 and the remaining assemblies 120, 140, 160 of the concentrator, ashave been previously described herein. This axis may be seen in FIG. 7as reference axis 180A. In this manner, movement and alignment of thesolar concentrator 101 relative to the positioning of the sun may begreatly facilitated and simplified, as the need to individually aligneach of the assemblies relative to one another is not routinelynecessary for purposes of merely tracking the sun. In certainembodiments, the drive bracket 181 may be configured so as to permitpivoting of the parabolic trough assembly 120 and the secondaryreflector assembly 160 about an arc of up to 270 degrees around the soleaxis. In other embodiments, varying degrees of rotation, substantiallygreater than or less than 270 degrees may be provided, as may bedesirable for particular applications. Such will tracking and movingcapabilities will, of course, be described in further detail below.

According to various embodiments, as may be seen perhaps best from FIG.7, at least a portion of the drive mounting bracket 181 may beoperatively connected adjacent a portion of the support member 114 ofthe base assembly 110. The drive mounting bracket 181 in certainembodiments, may be operatively connected proximate an upper portion ofthe support member 114, while in other embodiments, the drive mountingbracket 181 may be otherwise positioned relative to the support member,as may be desirable for a particular application. It should beunderstood, however, that in any of these and still other embodiments,the drive mounting bracket 181 should be positioned such that a pivotpoint defined thereby (as described in further detail below) is locatedat the center of gravity of the solar concentrator 101 in its entirety.In this manner, the work load of the rotating motor (e.g., a motor thatrotates the concentrator 101, in particular the parabolic troughassembly 120, the absorber tube 140, and the secondary reflectorassembly 160, via the mounting assembly 180, to track or follow themovement of the sun as it passes across the sky) is minimized. Suchpositioning at the concentrator's center of gravity (or substantiallythereby) enables the solar concentrator 101 to avoid “parasitic” loadsthat oftentimes adversely impact various devices of the prior art.

Remaining with FIG. 7, is may be seen that the drive mounting bracket181 according to various embodiments is configured to receive at least aportion of a standard gear box or hydraulic drive system (both shown asexemplary 183). It should be understood that any of a variety of gearbox, drive systems, or motors may be incorporated, as such are commonlyand understood in the art. In any of these and still other embodiments,however, any of a variety of shaft sections formed by and driven by thegear box, drive system, or motor will substantially align to define arotation axis that corresponds to the pivot point previously describedherein. In this manner, the standard gear box or hydraulic drive systemis configured, according to various embodiments, such that any shaftsections driven thereby rotate substantially about the center of gravityof the solar concentrator 101 in its entirety.

Although not particularly illustrated in FIG. 7, it should be furtherunderstood that the mounting assembly 180 described above may beconfigured with at least one bearing assembly having an upperpolyurethane insert and a lower polyurethane insert. These inserts,according to various embodiments, are configured to engage one anotherand form a circular opening, the center of which the sole pivot axis180A of the collector in its entirety extends through. In certainembodiments, the polyurethane inserts can be captured and housed by abushing cover at their tops and sides and a bottom flange that is inturn attached to the upright support member 114 of the base assembly110. In other arrangements, the bearing assembly can include a rollerbearing. In still other embodiments, the bearing assembly and/ormounting assembly 180 may be configured in any of a variety of ways,provided such facilitates controllable pivoting of the parabolic troughassembly 120 and the secondary reflector assembly 160 and the absorbertube 140 mounted relative thereto.

Turning now to FIG. 4, the central bracket 184 according to variousembodiments is illustrated. As may be seen, in at least the illustratedembodiment, the central bracket 184 is rectangular in shape, with anupper portion configured to fixedly receive at least one rotating shaftsegment. In this and still other embodiments, while the central bracket184 may be alternatively shaped or sized, it should be understood thatat least a portion of the central bracket is configured so as to fixedly(e.g., preventing relatively rotation there-between) receive therotating shaft segment. It is, of course, in this manner, according tovarious embodiments that the rotation of the rotating shaft segment(e.g. via an exemplary drive mechanism, as previously described herein)causes a corresponding rotation of the solar concentrator 101 and theassemblies comprised therein, as will be described in further detailbelow.

Remaining with FIG. 4, a trough bracket 186 is illustrated, whichaccording to various embodiments provides an operative linkage betweenthe central bracket 184 and the parabolic trough assembly 120, each ofwhich as previously described herein. The trough bracket 186 andassociated components may also be understood with reference to FIG. 5A.In certain embodiments, the trough bracket 186 may be rectangular inshape, although alternatively shaped configurations may be substituted,as desirable for a particular application. In certain embodiments, atleast a portion of the assembly 120 is fixedly attached to a lowerportion of the bracket 186, while an upper portion of the bracket isfixedly attached to the central bracket 184. In this manner, rotation ofthe exemplary drive mechanism, as previously described herein may betransferred between brackets 184, 186, ultimately to the trough assembly120. In other embodiments, a respective end (e.g., 130, 131) of thestructural frame member 129 of the trough assembly 120 is that portionwhich is fixedly attached to the bracket 186.

While in at least the embodiment illustrated in FIG. 4 and otherembodiments, at least a portion of the assembly 120 is fixedly attachedto the trough bracket 186, it should be understood that in still otherenvisioned embodiments, the central bracket 184 may be configured fordirect connection to the assembly 120, without the need for anintermediate trough bracket 186, as described herein. However, forvarious reasons, generally including the non-limiting examples of adesire to simplify maintenance, minimize structural impedance ofsunlight rays, and/or avoid repeated realignment of a particularassembly (e.g., assembly 120, to for example correct sunlight incidentangles) separate brackets like bracket 186 are often incorporated withinassembly 180.

Looking further at FIG. 4, an absorber tube bracket 188 is illustrated,which according to various embodiments provides an operative linkagebetween the central bracket 184 and the absorber tube 140, each of whichas previously described herein. An isolated illustration of the absorbertube bracket 188 alongside the absorber tube 140 is also provided inFIG. 4A. In certain embodiments, the absorber tube bracket 188 may berectangular in shape, although alternatively shaped configurations maybe substituted, as desirable for a particular application. In certainembodiments, beyond its rectangular or otherwise shape, the bracket 188may further incorporate (as a unitary piece, or separately) one or moreelongate tube support members 189, which extend generally from an upperportion of the bracket 188 to the absorber tube 140. Such supportmembers 189 serve as an additional intermediary (often to minimize solarray disturbance, due to their slimness) between the bracket 188 and theabsorber tube 140. However, it should be understood that in any of theseembodiments, each of the respective elements (e.g., 188, 189, 140, etc.)are all fixedly attached relative to one another so as to transfer therotational force from the shaft segments (as driven by the exemplarydrive mechanism, as previously described herein) to the absorber tube140.

In certain embodiments, at least a portion of the absorber tube 140 isfixedly attached to an upper portion of the bracket 188 (or one or moresupport members 189, as described above), while a lower portion of thebracket is fixedly attached to the central bracket 184. However, inother embodiments, at least a portion of the absorber tube 140 may beinstead fixedly attached directly to the central bracket 184, withoutthe need for an intermediate absorber tube bracket 188 and/or one ormore support members 189, as described herein. However, for variousreasons, generally including the non-limiting examples of a desire tosimplify maintenance, minimize structural impedance of sunlight rays,and/or avoid repeated realignment of a particular assembly (e.g.,assembly 120, to for example correct sunlight incident angles) separatebrackets like bracket 188 are often incorporated within assembly 180.

Returning specifically to FIG. 4, a reflector support bracket 190 isillustrated, which according to various embodiments provides anoperative linkage between the central bracket 184 and the parabolictrough assembly 120, each of which as previously described herein. Incertain embodiments, the reflector support bracket 190 may berectangular in shape, although alternatively shaped configurations maybe substituted, as desirable for a particular application. In certainembodiments, beyond its rectangular or otherwise shape, the bracket 190may further incorporate (as a unitary piece, or separately) one or moreelongate tube support members 192, which extend generally from at leasta portion of the bracket 190 to the trough bracket 186. Such supportmembers 192 provide an intermediary connection (often to minimize solarray disturbance, due to their slimness) between the reflector supportbracket 190 and the trough bracket 186, from which it receives support.Notably, in certain embodiments, the reflector support bracket 190 isoperatively fixed to the trough bracket 186 as opposed to the centralbracket 184 so as to directly fix the positional relationship betweenassemblies 120, 160, and more particularly the two mirrors 122, 162,contained therein. In this manner, misalignment of the two mirrors,respective to one another, may be further minimized according to certainembodiments. However, it should be understood that in still otherembodiments, each of the respective elements (e.g., 190, 192, 186, etc.)may be fixedly attached relative to one another in alternative fashions,as may be desirable for a particular application.

From FIG. 5, it should be further understood that at least a portion ofthe bracket 190 is fixedly attached to at least a portion of thesecondary reflector assembly 160. In certain embodiments, a respectiveend (e.g., 170, 171) of the structural frame member 169 of the assembly160 is that portion which is fixedly attached to the bracket 190.However, in other embodiments, alternative portions of the assembly 160may be attached, via any of a variety of mechanisms, to the bracket 190.It should be understood that for any of these described and still otherembodiments having a reflector support bracket 190, the bracket 190 mustbe in some manner fixedly attached, albeit generally indirectlyaccording to certain embodiments (e.g., via the trough support bracket186), to the central bracket 184, such that a rotation of the centralbracket via one or more of the previously described drive mechanisms,causes a corresponding rotation of the secondary reflector assembly 160.

Based upon the preceding description, it should be understood that theconfiguration of the mounting assembly 180, as described, althoughvariable in certain embodiments, should at least fixedly position eachof the trough assembly 120, the absorber tube 140, and the secondaryreflector assembly 160 relative to one another, so as to minimize theneed for refocusing and/or realignment, both in the short term (e.g.,for example, when the concentrator 101 is adjusted to track the sun) andin the long term (e.g., for example, when external fluctuations overtime vary mounting tolerances, warp one or more of the mirrors, or shiftthe foundational base assembly 110). All of these elements, via themounting assembly 180, are coupled to an exemplary drive mechanism (ashas been previously described herein) via a single interface, namely thedrive bracket 181 of the assembly 180, thereby enabling concurrent andcorresponding rotation of the aforementioned assemblies (e.g., 120, 140,160) without altering the alignment there-between. In this manner,various embodiments of the solar concentrator 101 provide a simplisticand efficient mechanism that not only remains aligned with a greaterdegree of consistency, but also recaptures stray reflected light raysthat initially miss the absorber tube 140 by reflecting them thereto viathe mirror 162 of the secondary reflector assembly 160.

Operation and Exemplary Configurations of Various Embodiments

In operation, one of the exemplary drive mechanisms of the solarconcentrator 101 may be activated, whether via a standard gear boxassembly (not shown) or a hydraulic drive assembly (also not shown),each as commonly known and understood in the art. However, in contrastwith conventional solar concentrators and solar collection systems,activation of the exemplary drive mechanism will rotate the solarconcentrator 101 in its entirety as a single unitary structure, due atleast in part to the orientation of the mounting assembly 180, aspreviously described herein, about the center of gravity of the solarconcentrator. In this manner, not only does rotation of the solarconcentrator 101 cause a corresponding rotation of the parabolic troughassembly 120, but it also causes a corresponding and comparable rotationof the absorber tube 140, the secondary reflector assembly 160, and themounting assembly 180, as all previously described herein. It should beunderstood that this unitarily linked rotation of the solar concentrator101 is facilitated at least in part in various embodiments by thesimplicity of the mounting assembly 180 and in particular, theconfiguration of the central bracket 184 about the center of gravity ofthe solar concentrator, as previously described herein.

Consider for example the solar concentrator 101 of FIG. 4, asillustrated in a first orientation, which may correspond, for example,to a time of day in which the sun is relatively high in the sky. In thefirst orientation, the parabolic trough assembly 120 is oriented suchthat incident light rays 14 from the sun (not shown) align with themirror 122 of the assembly and reflect therefrom as reflected light rays15, which will converge upon the absorber tube 140. Any misalignment ofthe solar concentrator 101 in the first orientation may, in certainembodiments, adversely impact the efficiency with which the reflectedrays 15 converge upon the absorber tube 140. However, as has beendescribed previously herein, with the unitary mounting configuration ofthe assemblies 120, 160, both relative to the absorber tube 140, anysuch in-efficiencies due to minor misalignment may be counteracted asthe mirror 162 of the secondary reflector assembly 160 redirects strayreflected rays 15 back toward the absorber tube 140. It should beunderstood, from viewing FIG. 5 in comparison to FIG. 4, that as the suntravels across the sky, the solar concentrator 101 may be moved from thefirst orientation into a second orientation (or still into and throughany of a plurality of other orientations, not shown), such that themirrors 122, 162 remain properly aligned with the sun. Notably though,in any of these and still other embodiments, because the mirrors 122,162 and the absorber tube 140 are all fixedly mounted relative to oneanother, relative misalignment errors, particularly those caused bychanging the orientation of the solar concentrator 101 to track the sun,are greatly minimized. In certain embodiments, the movement may beprovided across a range of approximately 270 degrees of rotation,although in other embodiments the movement may be substantially lessthan or even substantially greater than 270 degrees of rotation, as maybe desirable for particular applications.

Referring now to FIG. 8, the solar concentrator 101 of at least FIGS.3-4 is further illustrated, as such may be combined according to variousembodiments into a solar concentrator assembly 1001. In at least theillustrated embodiment, the assembly 1001 comprises three solarconcentrators 101, as previously described herein. Of course, in otherembodiments, the assembly 1001 may comprise any of a variety of numbersand orientations of solar concentrators 101, as may be desirable for aparticular application. As may be seen from at least FIG. 9, in certainembodiments, when so combined, each of the solar concentrators 101within the assembly 1001 may share a portion of at least one of its baseassemblies 110 with an adjacently positioned solar concentrator.However, in other embodiments, the base assemblies 110 may not be soshared. Such configurations, and even others that may be envisioned, arecommonly known and used in the art for combining multiple solarconcentrators 101 into assemblies for “farming” solar thermal energy,and as such, are largely provided and described herein for purposes offull disclosure.

Turning now to FIGS. 10-12, multiple solar concentrators 101, asillustrated in at least FIGS. 3-4 are further illustrated, combinedaccording to still additional embodiments into a solar concentratorassembly 2001. Such assemblies 2001 may comprise a plurality ofconcentrators 101, numbering in the hundreds, if not thousands, as maybe desirable for a particular application. Still further, suchassemblies 2001 may comprise multiple rows, each having a plurality ofconcentrators 101, although in at least the illustrated embodiment, onlyan exemplary single row is depicted. It should be understood that, aswith the assembly 1001 configurations described above, the assembly 2001configurations are also likewise generally commonly known and used inthe art for combining a plurality of solar concentrators 101 forpurposes of “farming” solar thermal energy, as has been previouslydescribed herein.

CONCLUSION

Many modifications and other embodiments of the invention set forthherein will come to mind to one skilled in the art to which thisinvention pertains having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the invention is not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

That which is claimed:
 1. A solar collector system, said systemcomprising: an absorber tube; a primary reflector having a primaryreflective surface portion configured to substantially reflect one ormore light beams making contact therewith substantially toward theabsorber tube; and a secondary reflector having a secondary reflectorsurface portion configured to reflect the one or more light beamsreflected from the primary reflector further toward the absorber tube,wherein the absorber tube is positioned intermediate the primaryreflector and the secondary reflector, such that the absorber tube isconfigured to collect one or more of the light beams reflected from theprimary reflector surface portion and one or more of the light beamsreflected from the secondary reflector surface portion.
 2. The solarcollector system of claim 1, said system further comprising a frameassembly configured to define a unitary pivot axis, wherein the primaryreflector, the secondary reflector, and the absorber tube areoperatively attached to at least a portion of the frame assembly thefirst support member such that the primary reflector, the secondaryreflector, and the absorber tube rotate as a single unit, said singleunit being configured to rotate substantially about said unitary pivotaxis whereas the primary reflector, the secondary reflector, and theabsorber tube each remain stationary relative to one another so as tominimize misalignment there-between.
 3. The solar collector system ofclaim 2, wherein said unitary pivot axis substantially corresponds witha center of gravity of said single unit formed by the primary reflector,the secondary reflector, and the absorber tube.
 4. The solar collectorsystem of claim 3, wherein longitudinal axes of the secondary reflectorand the absorber tube are offset relative to said unitary pivot axis. 5.The solar collector system of claim 2, wherein: the frame assemblycomprises a first support member and a second support member; the firstsupport member comprises at least one elongate member having a distalend, adjacent to which said secondary reflector is operatively mounted,so as to offset a longitudinal axis of the secondary reflector from saidunitary pivot axis a distance corresponding generally to a length ofsaid at least one elongate member; and the second support membercomprises at least one elongate member having a distal end, adjacent towhich said absorber tube is operatively mounted, so as to offset alongitudinal axis of the absorber tube from said unitary pivot axis adistance corresponding generally to a length of said at least oneelongate member.
 6. The solar collector system of claim 5, wherein saidlength of said at least one elongate member of said first support memberis substantially greater than said length of said at least one elongatemember of said second support member, such that said absorber tube ispositioned substantially intermediate said primary reflector and saidsecondary reflector.
 7. The solar collector system of claim 2, whereinsaid unitary pivot axis is configured to permit concurrent rotation ofsaid primary reflector, said secondary reflector, and said absorber tubethrough an angle of up to 270 degrees.
 8. The solar collector system ofclaim 1, wherein said primary reflector comprises a substantiallyparabolic trough reflector, said substantially parabolic troughreflector defining a substantially parabolic arc, said substantiallyparabolic arc having a focal point.
 9. The solar collector system ofclaim 8, wherein said substantially parabolic arc has a diameter lyingin a range of from approximately three meters to approximately sevenmeters.
 10. The solar collector system of claim 9, wherein said diameteris approximately five meters.
 11. The solar collector system of claim 8,wherein said focal point defines a focal line, said focal line beingsubstantially aligned with a longitudinal axis of said absorber tube.12. The solar collector system of claim 11, wherein said focal line andsaid longitudinal axis of said absorber tube are positioned a distancerelative to said parabolic trough reflector, said distance lying in arange of from approximately 1.5 meters to approximately 4.5 meters. 13.The solar collector system of claim 12, wherein said distance is betweenapproximately 2.0 and 2.5 meters.
 14. The solar collector system ofclaim 8, wherein said focal point is calculated by dividing a square ofa diameter of the parabolic arc by the result of multiplying a depth ofthe parabolic arc by sixteen.
 15. The solar collector system of claim 8,wherein said substantially parabolic trough reflector is formed from twodistinct mirror panels, each of said mirror panels being positioned onopposing sides of a unitary pivot axis substantially parallel to alongitudinal axis of said primary reflector.
 16. The solar collectorsystem of claim 1, wherein said secondary reflective surface portion ofsaid secondary reflector is formed by a substantially reflectivecoating, said reflective coating having unidirectional reflectiveproperties, such that light beams may pass there-through substantiallyunhindered in at least one direction.
 17. The solar collector system ofclaim 1, wherein said secondary reflector comprises a substantiallyparabolic trough reflector, said substantially parabolic troughreflector defining a substantially parabolic arc, said substantiallyparabolic arc having a focal point.
 18. The solar collector system ofclaim 17, wherein said substantially parabolic arc has a diameter lyingin a range of from approximately one meters to approximately threemeters.
 19. The solar collector system of claim 17, wherein said focalpoint defines a focal line, said focal line being substantially alignedwith a longitudinal axis of said absorber tube.
 20. The solar collectorsystem of claim 19, wherein said focal line and said longitudinal axisof said absorber tube are positioned a distance apart from saidsecondary reflector, said distance lying in a range of fromapproximately 0.25 meters to approximately 2.5 meters.
 21. The solarcollector system of claim 17, wherein said secondary reflector is formedfrom two distinct mirror panels, each of said mirror panels beingpositioned on opposing sides of a unitary pivot axis that issubstantially parallel to a longitudinal axis of said primary reflector.22. The solar collector system of claim 17, wherein said primaryreflector comprises a substantially parabolic trough reflector, saidsubstantially parabolic trough reflector defining a substantiallyparabolic arc, said substantially parabolic arc having a focal point.23. The solar collector system of claim 17, wherein said secondaryreflector comprises a dual parabolic trough reflector, said dualparabolic trough reflector defining at least two substantially parabolicarcs, each substantially parabolic arc having a focal pointcorresponding substantially with a longitudinal axis of said absorbertube.
 24. A solar collector system, said system comprising: a frameassembly configured to define a unitary pivot axis; a primary reflector,the primary reflector being operatively attached to at least a portionof said frame assembly; a secondary reflector, the secondary reflectorbeing operatively attached to at least a portion of said frame assembly;and an absorber tube, the absorber tube being operatively attached to atleast a portion of said frame assembly such that the absorber tube ispositioned substantially intermediate the primary reflector and thesecondary reflector, wherein the primary reflector, the secondaryreflector, and the absorber tube form a single unit, said single unitbeing configured to rotate substantially about the unitary pivot axiswhereas the primary reflector, the secondary reflector, and the absorbertube each remain stationary relative to one another so as to minimizemisalignment there-between.
 25. A method of using a solar collectorsystem to maximize collection of light beams directed thereon by anexternal light source, the method comprising the steps of: (A) providinga system comprising: (1) a frame assembly configured to define a unitarypivot axis; (2) a primary reflector, the primary reflector beingoperatively attached to at least a portion of the frame assembly; (3) asecondary reflector, the secondary reflector being operatively attachedto at least a portion of the frame assembly; and (4) an absorber tube,the absorber tube being operatively attached to at least a portion ofthe frame assembly such that the absorber tube is positionedintermediate the primary reflector and the secondary reflector and theprimary reflector, the secondary reflector, and the absorber tube form asingle unit; (B) positioning said single unit in a first orientation,said first orientation corresponding to a position at which, during afirst period of time, a volume of light beams directed onto said primaryreflector is maximized; and (C) rotating said single unit to a secondorientation, said second orientation corresponding to a position atwhich, during a second period of time different from said first periodof time, said volume of light beams directed onto said primary reflectoris maximized, wherein said rotating occurs about said unitary pivotpoint such that the primary reflector, the secondary reflector, and theabsorber tube within the single unit each remain stationary relative toone another so as to minimize misalignment there-between.